Infrared video tracking for use in projecting onto dynamic water features

ABSTRACT

A projection system for projecting a still or video image onto a liquid surface. The system includes an agitation mechanism selectively operable to generate gas bubbles on the liquid surface. The system includes a tracking system tracking a location, size, and shape of the gas bubbles on the liquid surface. The system also includes a projector projecting a video stream onto the gas bubbles based on the location, shape, and size of the area of the liquid surface containing the gas bubbles. The tracking system may include an infrared (IR) light source delivering IR light to the liquid surface and an IR video camera receiving a portion of the delivered IR light that is reflected by the gas bubbles. The reflected IR light defines a dynamic projection surface presented by the gas bubbles on the liquid surface by defining a boundary on the liquid surface about the gas bubbles.

BACKGROUND

1. Field of the Description

The present description relates, in general, to visual display and projection systems, and, more particularly, to a method and system for projecting light, including video images, onto dynamic features of a surface of water (or other liquid) such as an upper surface of a pool of water or a fountain or curtain of water. The “dynamic features” may be provided with air (or other gas) bubbles that change in size, quantity, and/or location on the liquid surface over time to provide a moving and varying projection surface or target on the liquid surface.

2. Relevant Background

There is an ongoing demand for ways to create visually interesting and exciting displays that involve water. Throughout the world, fountains have been developed and installed that entertain spectators with jets and fans of water that have unique shapes. The fountains may even be operated in time with music and a light show to provide a unique, choreographed display. In some indoor displays, mist screens have been used to provide a curtain that can be used as a display surface using a rear projection system, and such display systems have been used regularly at large trade shows and other events to provide an interesting way to present information and to entertain a crowd.

Current examples of video projections on water screens (mist curtains, fountain jets, and the like) rely on a pre-programming of the water to suit the projected images (e.g., spray water upward where images are projected) and/or pre-programming of the video stream to project onto the water surfaces that are changing over time. The bubbles or agitated portions of the fountain spray or mist screen provide the better surfaces for reflecting the light from the projector, with light striking more laminar flowing portions be transmitted through the water. In many applications, the audience may see the light that is transmitted through the water and the effect or illusion may be spoiled if too much light is allowed through the water-based projection screen. Another issue with such display systems is that the reflected image may be of lower quality if not enough light is reflected or the viewed image may appear to have holes or gaps where less or no light within a projected image is reflected such as in areas with less or no bubbles (or laminar flow).

In contrast, though, larger bodies of water present a more difficult challenge for the designer of a display. For example, a designer may wish to use a body of water in a pool or pond to display light or media (e.g., a video or still image projected from a projector (“projected images”) or may wish to display images in a channel of a water ride as a boat/vehicle carrying passengers travels through the water. The upper surfaces of these bodies of water are generally planar or smooth, and water is generally transparent or at least translucent to light. As a result, light projected onto the surface of these bodies of water is reflected well only at a specific, narrow angle with most of the incident light being transmitted rather than reflected, resulting in a large percentage of the incident light traveling through the water to the bottom of the pool or channel containing the water. At this point, the light may be reflected upward off the bottom to be viewed by spectators (e.g., people on or nearby the body of water).

A display on the bottom or sides of the pond/channel is generally not desirable as the projected content, such as still image or video, appears to be on the bottom of the pool/channel. This may make the image unclear or distorted as it has to be viewed through a depth of water which detracts from its clarity. Further, lighting the bottom of the pond/channel often will be undesirable as this may reveal equipment such as pumps and nozzles used to create a fountain or a track used to move a boat through an amusement park ride. Additionally, these lower surfaces under the water often are not useful for reflecting light in a predictable or desirable manner such as the bottom of a natural lake or river that may have a bottom covered with mud, rock, and plants. As a result, the surfaces of lakes, ponds, and rivers (all of which may be manmade such as a channel defining a river of water for an amusement park ride) have previously not been used as display surfaces for light-based shows or projected media.

SUMMARY

Briefly, the following description teaches systems and methods for projecting on a liquid surface such as upon an upper surface of a pond, a river, or water in a channel (such as a channel of an amusement park ride), on a “front” surface of a mist screen or fountain spray, or a surface of another body of water. A dynamic water feature or dynamic projection surface is formed on the liquid or water surface (with water often used interchangeably for liquid in this description but not in a limiting manner) by providing a plurality of bubbles such as with an air or other gas stream provided by a bubble generation system.

Liquids such as water are typically translucent or transparent to light, and the dynamic water feature is provided to form a projection surface or “screen” on the surface of the body of water by adequately agitating or disturbing the surface to create a diffuse reflecting surface. The agitated portion of or set of bubbles on the surface reflect a significant fraction of the projected light over a wide range of viewing angles to an observer, rather than simply allowing the light to be transmitted to the bottom of the body of water. Typically, the bubbles are caused to change in size, number, and/or location over time such that the bubble-based projection surface varies over time, too, to provide a dynamic water feature or dynamic projection surface.

An agitation (or bubbles) tracking system is used to determine the present location and size of the dynamic projection surface (where are the bubbles on the surface and what is the shape and size of agitated portion of the liquid surface?). A video mask is generated such that, when an image (still or video) is projected onto the liquid surface with a projector using the mask, the unmasked/unfiltered portion of the image is projected (in large part) onto the dynamic projection surface (or the water feature provided by the bubbles) and not on the other portions of the liquid surface. The tracking system may use an infrared (IR) video camera to “see” the bubbles on the liquid surface, and the output of this IR video camera may be used to create the video mask. In this manner, light is projected on the dynamic water feature to create a higher quality display on a water surface without the undesired transmittance of light through other portions of the water surface (e.g., to avoid spoiling the effect by illuminating the bottom of a pool/channel or transmitting light through a mist screen or fountain spray).

More particularly, a projection system is provided for projecting a still or video image onto a liquid surface. The system includes an agitation mechanism that is selectively operable to generate a plurality of gas bubbles on or near the liquid surface. The system also includes a tracking system tracking at least a location of the gas bubbles on or near the liquid surface. Further, the system includes a projector projecting a video stream onto the gas bubbles based on the location determined by the tracking system.

The tracking system may include an infrared (IR) light source delivering IR light to the liquid surface and an IR video camera receiving a portion of the delivered IR light that is reflected by the gas bubbles. In operation, the reflected IR light defines the location of the gas bubbles on the liquid surface and, more particularly, the reflected IR light defines a boundary on the liquid surface around the gas bubbles defining the location of the gas bubbles and a size and shape of a dynamic projection surface provided on the liquid surface by the gas bubbles. In some cases, the projecting by the projector further includes generating a video mask based on the boundary around the gas bubbles and applying the video mask to the video stream. In such cases, an unmasked portion of the video stream is projected by the projector onto a portion of the dynamic projection surface and a masked portion of the video stream is projected by the projector onto portions of the liquid surface outside the boundary. Since the boundary (or projection surface) is “dynamic,” the tracking system typically is operated at least periodically to update the boundary and the projecting by the projector includes updating the video mask based on the updates to the boundary.

In some embodiments of the system, the liquid surface is a horizontal planar surface of a body of water (such as on a pool, a pond/lake, a channel, or the like). In these embodiments, the agitation mechanism may be a bubble generator operable to change, over time, at least one of: the location of the gas bubbles, a size of an area of the liquid surface containing the gas bubbles, and a shape of the area containing the gas bubbles.

In one exemplary application, the tracking system includes an IR camera generating an infrared bubble key. In this application, the system further includes a video processor generating a video mask from the infrared bubble key. During operation, the projecting by the projector includes inserting a portion of the video stream onto the infrared bubble key, whereby the inserted portion is projected onto a portion of the liquid surface including the location of the gas bubbles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D are overhead or top schematic views of a display or projection system of an embodiment used to display or project an image onto a dynamic water feature (or projection surface) detected and provided on surface of water in a pool/basin, with FIG. 1A showing the display system with bubble generation system operating and as seen in visible light, FIG. 1B showing the display system of FIG. 1A as viewed/imaged by an IR video camera, and FIGS. 1C and 1D showing operation of the bubble generation system to provide a dynamic water feature, a tracking system detecting the size, shape, and location of the dynamic water feature/projection surface, and a projector projecting a video that is dynamically masked based on the detected dynamic water feature (bubble pattern);

FIG. 2 is a side view (with schematic or functional aspects) of a projection system during operation to detect a dynamic projection surface on a liquid surface using an IR video camera and to project video onto the liquid surface that is dynamically masked to suit the detected projection surface (e.g., project unmasked portion of video stream onto the dynamic projection surface generated by a bubble generation system);

FIG. 3 is a functional block diagram of a projection system providing IR-based tracking of a dynamic water feature and, in response, generating a video image projected onto the water feature; and

FIG. 4 illustrates a flow diagram of an exemplary projection process of the present description such as one that may be carried out during operation of the projection system of FIG. 3.

DETAILED DESCRIPTION

Briefly, the present description is directed toward methods and systems for projecting light such as a laser show or images (video or still) from a projector upon a liquid surface for viewing by viewers or spectators. There is a growing need to project digital video on dynamic water screens and fountains. Typically, the video projection system projects on the back side of the water screen and is generally focused on the entire screen with no way to dynamically mask the video to the moving water.

In contrast, the display systems described herein uses infrared light sources to illuminate the viewer side of the fountain, water feature, or bubble screen (“liquid surface” of a body of water). This infrared illumination is reflected back to a video camera that is sensitive to the infrared wave length. When viewed by the IR sensitive camera, the atomized and turbulated water is differentiated from the background (or non-agitated portion of the liquid surface). The display system uses the output of the IR video camera to pull or form a video “key” for the present/existing state of the liquid surface. This key is then used to process (e.g., to mask) the projection media in real-time so that it only projects on the dynamic flowing surface of the water feature. In other words, a tracking system is provided in the display system for determining in real time the shape, size, and location of a dynamic water feature (or projection surface) on the liquid surface, and the display system uses this information to generate a video mask such that a projector projects an image (the unmasked or non-filtered portion of the overall video image stream) onto the dynamic water feature (video black (or masked/filtered portion) projected onto the remaining portions of the liquid surface) such that the majority of the light from the projector strikes the bubbles/agitated areas on the liquid surface.

Water by itself absorbs the bulk of the infrared spectrum, which makes detection of the digital infrared imagery of the surface of water difficult. Water reflects primarily in blue wavelengths and somewhat less in all other wavelengths. By aerating the water with bubbles, the short wave infrared reflection is increased because bubbles have a different refractive index than the surrounding surface material (water). The inventor recognized that this differential can be seen by infrared (IR) sensitive digital video cameras. Hence, the agitation tracking system includes IR emitters that flood the liquid surface with IR beams, an IR video camera for capturing IR beams reflected from the liquid surface (an “IR image” of the liquid surface), and one or more processing modules (run by a processor of the display system) for determining the size, shape, and location of the dynamic water feature (or projection surface provided by the bubbles/agitation).

The display system (and technique) allows for different configurations of a bubble generation system to be used to form the dynamic water features. In some cases, the display system may include a fountain or water/mist screen for providing a liquid surface. In some cases, bubble generation can involve aerating the water in a single vertical fountain by injecting pressurized air in to the water stream prior to the fountain nozzle. The resulting frothy turbulence in the water flow changes the visual appearance of the water to white. In addition, the air bubbles allow for the reflectance of a small portion of the infrared spectrum. These air injectors are commonly used in fountain nozzles as well commercial aeration systems.

In other applications, the liquid surface may be a relatively planar surface of a body of water, either still or flowing, in a basin, pool, channel, or other open liquid container, and the liquid may be water or some other transparent (or at least translucent) liquid. A dynamic projection surface or screen is created in a portion of this liquid surface that effectively reflects a significant portion of light from a projection device(s) to allow a viewer to see the images as reflected light. To this end, the bubble generation system (or surface agitation mechanism) may be an aeration system used to generate the projection surface within or as part of the liquid surface (e.g., numerous air bubbles act to reflect the projected light to a viewer). Numerous special effects may be created by controlling the operation of the surface agitation mechanism, e.g., the amount or rate of agitation to create a sharper image or a hazier image, turning the mechanism on and off quickly or slowly to present/remove an image rapidly or with a fade in/out effect, selective activation of portions of the agitation mechanism to cause the projection surface to move across the liquid surface and/or change in shape and/or size, and so on.

In some applications, the projection method is used to project onto a dynamic projection screen or surface provided as part of the top or upper surface (a liquid surface) of a volume of a liquid (such as water or other transparent to translucent liquid) in a pool, channel, or other container. In other cases, the same or similar techniques may be applied to a surface of a body of water that may be more vertical such as a mist screen or a spray provided by one or more nozzles of a fountain. The projection surface is “dynamic” in that it generally is provided or generated so as to be changing in at least one of size, shape, location, or other characteristics (such as gas bubble number, size, and/or density on or near the liquid surface). To this end, the bubble generation system (or agitation mechanism) is operated to cause the projection surface to be dynamic and to vary over time.

A tracking system is used to track these changes in the projection surface or area and to allow the projection surface to be defined and/or mapped to the liquid surface, e.g., to define at least the boundaries or outline of the projection surface. The boundary of the projection surface provides the size, shape, and location of the majority of the bubbles or the agitated portion of the liquid surface that is the most useful for front projection (to reflect light project upon the liquid surface). An IR light source is used to flood the liquid surface with IR beams or light, and an IR video camera is positioned adjacent the projector so as to capture IR beams or light in the IR wavelengths that are reflected from the liquid surface to a location coinciding or at least proximate to the projector output (projection lens).

More specifically, the IR video camera captures IR beams or light reflected from gas bubbles on or near the liquid surface. The output of the IR video camera can then be processed to define the present or existing dynamic projection surface provided by such bubbles, and a video processor can generate a video mask to block (or project black) on the areas or portion of the liquid surface where bubbles are (for the most part) absent. The masked image allows an unmasked portion (or a portion mapped to a video key matching the defined shape, size, and location (or being somewhat smaller or larger and being the same or a differing shape)) to be projected upon the dynamic projection surface. The tracking system and video processor operate on an ongoing manner to track changes in the projection surface provided by the bubbles and to change the mask so as to cause the unmasked or projected image to change with the projection surface. In other words, the projected image changes in at least one of shape, size, and location to suit the tracked/detected changes in the dynamic projection surface.

The projection method and useful projection systems may be better understood with pool-based examples with reference to FIG. 1A to FIG. 2. FIGS. 1A-1D illustrate top or overhead views (in a simplistic manner) of a projection system in operating states 100A-100D. The projection system includes a pool filled with water (or other liquid) as shown by a pool edge 110 surrounding or adjacent a water surface 120 (upper or top surface of a body of water in the pool).

FIG. 1A illustrates the projection system 100A when a bubble generation system (not shown but likely located at the bottom of the pool in or with outlets in the water) operating to generate numerous gas (e.g., air) bubbles 124 that rise through the water until they are at the water surface 120 (and pop or the gas escapes after a generally short period of time). FIG. 1A illustrates the pool of projection system 100A in visible light conditions such as would be seen or viewed by a viewer along the pool edge 110 looking down into the pool 100A. At this point in system operations, the water surface 120 is not illuminated by IR light or by projected light from a video projector.

FIG. 1B, in contrast, illustrates the projection system 100B as “viewed” or “seen” by an IR video camera. FIG. 1B can be thought of as showing output of an IR video camera filming and/or focused upon the water surface 120. As shown, the bubbles 124 are readily visible in the IR video camera output with each bubble defined by its location and size (IR camera sees circles for each bubble of a particular diameter). The more laminar portions or areas free of bubbles 124 in water surface 120 are not seen or detected or appear dark in the IR video camera output indicating IR light is not reflected off of these portions of water surface 120. The inventor recognized that light projected onto the bubbles 124 would be more readily reflected and visible to a viewer of the pool and further understood that the output of the IR video camera shown in FIG. 1B can be processed to define a dynamic projection surface made up of all or a portion of the bubbles 124 (or coinciding at least partially with the location of the bubbles 124 on surface 120).

FIG. 1C shows the projection system 100C during operation to both track a dynamic water feature/projection surface and projection onto this tracked/defined surface. As shown, a bubble generation system is being operated to produce a plurality of bubbles 134 that rise up to the surface 120. An IR-based tracking system is used in combination with video processing of the IR video camera to define a dynamic projection surface 130, with its boundary enclosing all or a majority of the bubbles 134. The boundary defines the size, shape, and location of the projection surface 130 on the water surface 120. Note, the bubbles 134 provide an irregular shaped projection surface 134, but this can be accurately mapped to the water surface 120 by video processing of the LR video camera output.

The video processing of the IR video camera output can then be used to generate a video mask that may be used to project with a video projector (not shown) a video image (still and/or moving images) onto the water surface 120. More particularly, a mask is created based on the determined projection surface 130 so that a projected image (unmasked image) 140 is projected onto the projection surface 130 and bubbles 134. The projected or unmasked (i.e., projected light not blocked by a video mask) image 140 may take a variety of forms such as that shown or may simply be white or colored light or other imagery. Further, the projected image 140 may take the same shape, size, and location as that of the projection surface 130 or it may differ (e.g., be based on the surface 130 but be smaller to cause all or most of the projected light of image 140 to land on bubbles 134 or be a differing shape and so on to achieve a desired effect).

The other portions of the water surface 120 may have masked or filtered image/light 141 projected onto them by the projector (e.g., video black). By masking these portions of surface 120, the system 100C operates to control or limit illumination of the bottom of the pool (which may ruin the effect by showing the bubble generation system and other parts of the pool). Note, one projection surface 130 is shown with one projected image 140, but other embodiments may provide two or more surfaces and images 130 and 140 using one, two, or more projectors. The projection surface 130 is “dynamic” in that it may be moving as shown with arrows 131 and/or changing in shape and size such that tracking preferably is performed on an ongoing or at least periodic basis accompanied with updating of the video mask and projected/unmasked image 140 projected by the video projector.

With this in mind, FIG. 1D illustrates the projection system 100D at a later moment in time. The bubble generation system has operated to move or change, as shown with arrows 151, its output to provide bubbles 154 that may differing in location, quantity, size, number, and other characteristics such as density. The tracking system/video processor uses reflection of IR light from the bubbles 154 to detect or define a new projection surface 150. The boundary of which is mapped to surface 120 in the pool of system 100D. As shown, the projections surface 150 has moved away 151 from the location of the projection surface 130 and has also changed in shape and size.

Based on the defined projection surface 150, the video process of projection system 100D acts to create a video mask for use with a video stream. As a result, the video projector is operated as shown to project an image 160 onto all or portions of the bubbles 154 of the projection surface 150. Concurrently, the video mask acts to filter or mask portions of the projector light to project a masked/filtered image or portion (video black) 161 onto the water surface 120 in areas outside of the projection surface 150. Of course, a portion of the light of the projected image 160 may strike outside the projection surface 150 due to the variability of the bubbles 154 and the dynamic nature of the surface 150 as shown with arrows 151. In this manner as shown in FIGS. 1C and 1D, the projection system 100C and 100D can operate to react to changes in the projection surface and generate bubbles to map boundaries of a useful projection surface onto the water surface 120 and provide an unmasked projected image on the dynamic and varying bubbles 134, 154.

FIG. 2 illustrates a projection system 200 such as may be used to selectively project onto agitated or bubbling portions of a liquid surface (upper surface of a pool, channel, or other vessel/container for water or other liquids). For example, the system 200 could be used to provide the projection systems 100C and 100D shown in FIGS. 1C and 1D. The projection system 200 includes a pool or similar liquid container 210 in which a volume 212 of translucent to transparent liquid such as water is provided and with an exposed upper or top surface (“liquid surface”) 214.

A bubble generation system 218 is positioned within the pool 210 to generate gas bubbles that move up through the liquid 212 to the surface 214. The bubble generation system 218 may be operated by a show controller or the like to create projection surfaces with the bubbles by generating the bubbles in differing locations and/or changing the amount, size, and shape of the output bubbles. The bubble generation system 218 may be controlled based on a video stream concurrently provided to a projector 250 (or provided to the projector 250 with a delay selected to allow generated bubbles to reach the surface 214), e.g., generate bubbles in areas of the surface 214 mapped to imagery shapes, sizes, and locations of the image stream. For example, it may be desired to display a mermaid swimming about the pool 210, and the bubble generation system 218 may be operated to generate bubbles at surface 214 coinciding with the image of (or the pixels associated with) the mermaid in the video stream provide to the show controller or other controller of bubble generation system 218.

A tracking system is provided to determine where the bubbles from the bubble generation system 218 are breaking the surface 214 of the liquid body 212. The tracking system includes an overhead support structure 220 mounted over the pool 210. More significantly, the tracking system includes a source of IR light 231 in the form of a number of IR emitters 230 mounted to support structure 220. The IR light 231 is provided from emitters 230 so as to flood the liquid surface 214.

The tracking system further includes an IR video camera 240 with an input or receiving lens 241 focused onto the pool 210. Particularly, the IR video camera 240 is mounted onto or adjacent to the projector 250 such that its lens 241 is nearly coaxial with the projector output lens 251 such that the IR video camera 240 sees the liquid surface 214 as does the projector 250. As shown, the IR camera 240 receives IR light 235 reflected from the liquid surface 214, and, as discussed above, the IR light 235 is for the most part reflected from the bubbles on or agitated portions of the liquid surface 214 (and not the entire surface 214 unless bubbles are provided throughout as may be the case during some operating states of bubble generation system 218). The output stream of the IR video camera is provided to a controller for the projector 250 for processing to define a dynamic projection surface or water feature on the surface 214 associated with the reflected IR light 235.

The projection system 200 further includes a video projector 250 with its output provided via lens 251 to the liquid surface 214. This is shown with arrows 254 indicating that light from the projector 250 is projected to strike the entire liquid surface 214 of the pool 210. The projection system 200 processes the output of the IR video camera 240 to generate a video mask that is used such that the projector 250 outputs a video image that may be thought of as including a masked portion (video black) and an unmasked portion shown with arrows 256. In other words, a video stream may be mapped to the dynamic projection surface corresponding to reflected IR light 235 (and bubbles (not shown) on surface 214) such that all or a majority of the light from projector 250 is provided in output rays 256 with video black projected in other portions of the output 254 onto surface 214. As shown, the rays 256 from projector 250 are wholly contained within the boundaries of IR reflected light 235 but this is not a requirement to practice the invention.

With the above description in mind, it may be useful to restate some of the concepts the inventor has found useful in projecting on a dynamic water feature (with some of this explanation being restated from earlier remarks). The projection technique uses infrared light sources to illuminate the viewer side of the fountain, water feature (pool, channel, or other body of water with a horizontal liquid surface), or bubble screen. This infrared illumination is reflected back to a video camera that is sensitive to the infrared wave length. When viewed by the IR sensitive camera, the atomized and turbulated water is differentiated from the background. This allows for a video “key” to be pulled by video processing the output of the IR camera. This key can be used to process the projection media (video stream input to the projector controller) in real-time so that the projector is operated to only (or largely) project on the dynamic water feature provided by the bubbles of the liquid surface.

Water by itself absorbs the bulk of the infrared spectrum, which makes detection of the digital infrared imagery of the surface of water difficult. Water reflects primarily in blue wavelengths and somewhat less in all other wavelengths. By aerating the water with bubbles, the short wave infrared reflection is increased because bubbles have a different refractive index than the surrounding surface material (water). This differential can be seen by infrared sensitive digital video cameras.

The described projection technique (and projection system) allows for different configurations of the bubble generation system. In some cases, the water in a single vertical fountain is aerated by injecting pressurized air in to the water stream prior to the fountain nozzle. The resulting frothy turbulence in the water flow changes the visual appearance of the water to white. In addition, the air bubbles allow for the reflectance of a small portion of the infrared spectrum. These air injectors are commonly used in fountain nozzles as well commercial aeration systems. Examples of aeration nozzles include nozzles available from suppliers such as Crystal Fountains, Toronto, Ontario, Canada; Pond Place of Michigan, Inc. (EasyPro Fountain Nozzles or other aerating nozzles); and other manufacturers/distributors in the fountain or water display industry.

In some situations, it may be desirable to control surface aeration. In such implementations of a projection system, single or multiple sub-surface aeration techniques may be used in the projection system. There are many types of underwater aeration “bubblers” used to aerate water for a variety of commercial applications including sewage treatment, pond treatment, oxygenation, and the like. Some examples of sub-surface aerators that may be used as or as part of a bubble generation system/agitation mechanism in the projection system include Airmax® ProAir™ Membrane Diffuser Sticks from The Pond Guy (www.thepondguy.com); aerators provided for ponds, such as Kasco Aerators or the like, distributed by Pond and Garden Wholesalers (www.pondandgardenwholesalers.com); or other aerators provided by other manufacturers or distributors. These diffusers typically sit on the bottom of the water tank, lake, pond, pool, or the like. The upwelling of the bubbles draws surrounding water upward so as to continually mix the water. They can also be used in commercial aquariums to add oxygen to the water. Bubbles can be generated in different sizes from course to micro-bubbles depending on the requirements of the end use.

In embodiments of the described projection systems, a large array of underwater bubble “aerators” may be controlled allowing us to “draw” complex paths of bubbles on the surface of the water. In other words, the dynamic water feature or projection surface can have its boundary (shape and size) well defined and caused to change in shape or size as well as location over time. Each bubble aerator can be independently controlled from a digital show control system. These control systems are common in theme park and other applications. In one form of a projection system, a standard DVI (digital) video media may be used by the bubble generation system controller to directly drive a mapped array of solenoid valves to release groups of bubbles in synchronization with projected video. An example of an off-the-shelf DVI video interface would be a video micro converter (VMC) such as that provided by Traxon Technologies. This video micro converter takes DVI video and converts it to industry standard DMX digital control protocol. The DMX protocol can directly drive air solenoids of a bubble generation system (or one or more aerators).

In some applications of the projection system, the projection controller calculates the rise time of the bubbles. Then, the projected video is delayed by the projector controller to hit the liquid surface and the bubbles from the bubble generation system just as they reach the surface of the water (e.g., predict the about to be created dynamic projection surface rather than reacting to a tracked water feature provided by the bubbles). Alternatively, the video projector can be controlled such as with a shorter delay to hit the bubbles prior to them reaching the surface; thus, illuminating the bubbles underwater.

In another form of the invention, as discussed with reference to FIG. 2, an infrared sensitive digital video camera is used to look at the surface of the water from the POV of an associated video projector. The video camera is calibrated to look at the same area that the projector covers in its projection field. As the water is aerated with bubbles, the infrared sensitive camera “sees” the difference between the un-aerated water surface and the aeration bubbles. This difference image is processed to extract the aerated surface bubble field and then used as a “mask” in the video stream. The mask allows for video media to be projected accurately upon the bubbles on the surface of the water and not on the adjacent non-aerated water surface. Such control over the projection of the video by the projector is useful because allowing projection on the non-aerated surface can illuminate the bottom of the pool or containment area including the bubble system piping, hoses, and so on which may spoil the illusion of magical bubbles.

There are a number of control options that may be used as part of a projection system of the present description. For example, there are many IR “blob” detection techniques available including the Nintendo Wii and the Microsoft Kinect. Those skilled in the art will readily understand such control devices and know how to adapt these off-the-shelf tracking solutions to create an IR light source (or projector) and an IR video camera-based IR tracking system. Examples of a real-time IR tracking system used in an entertainment application that may be used in the projection systems may include: (a) the Spotlesslight® system provided by Spotless, LLC, Brooklyn, N.Y., USA; (b) the tracking system described in U.S. Pat. Appl. Publ. No., 2008/0316432, which is incorporated herein by reference; and (c) the tracking system of U.S. Pat. Appl. Publ. No. 2011/0001935, which is incorporated herein by reference (this product is a real-time infrared projector-camera system that can track a performer on stage and project light upon the performer or only on the background and not on the performer).

Another approach that could be used for part of the projection system control is detailed in U.S. Pat. No. 7,775,883, which is incorporated herein by reference. In this patent, a control is described that uses a projector-camera combination to detect movement visible to infrared cameras where the object is illuminated under appropriate infrared illumination. This technique could be applied as described herein by the inventor in a different manner to track bubbles that are illuminated under infrared light. In all cases, although the end entertainment technique may vary, the use of projector-camera based technology to track movement or detect change is accomplished. These techniques can be adapted to track the difference between air bubbles and the surrounding water surfaces.

FIG. 3 illustrates in functional block form a projection system 300 that is adapted for use in displaying images 316 to viewers on a dynamic feature 314 on a liquid surface 312. The liquid surface 312 is provided by a source 310 such as a fountain, a mist curtain/screen system, a pool, channel, or other structure (natural or manmade) for containing a volume of water, and so on. A surface agitation mechanism 318 is provided for responding to control signals 386 to agitate the liquid surface 312 to form the dynamic feature 314 such as with bubble generators, aerator nozzles, and the like, and the dynamic water feature or projection surface 314 typically changes over time such as in its shape, location, size, density, and so on based on operation of the mechanism 318.

An agitated area tracking system 320 is provided for determining how to define the dynamic feature in real time (e.g., to define the boundary and location of the feature 314 on surface 312). To this end, the tracking system 320 includes an IR light source 322 operating on an ongoing basis to flood the liquid surface 312 with IR light 323. The tracking system 320 further includes an IR-sensitive video camera 324 focused on the liquid surface 312 (in a manner similar to that of projector 360) to received IR light 325 reflected from the liquid surface 312, e.g., from the bubbles or agitated portions in liquid surface 312 associated with the dynamic water feature 314 formed by the agitation mechanism 318. The output 326 of the IR video camera 324 is transmitted to the video image (or projector) controller 340 for processing to control the projector 360.

In the projection system 300, a video projector 360 is used to project light 364 onto the liquid surface 312, with an unmasked image 316 being projected onto the dynamic feature 314. To this end, an image stream 348 for projection is provided by a video image controller 340, and the media 348 provided to the projector 360 is processed based on a video mask generated by the controller 340 using the IR camera output 326. Particularly, the projection system 300 includes a video server 330 providing a video stream 331 that is provided as input to the controller 340 and also to the show control system 370 (for use in controlling, in some cases, the agitation mechanism 318).

The controller 340 includes a processor(s) 342 that manages memory 350 (computer readable data storage or media devices that may store programs or code causing the computer/controller 340 to perform certain functions such as processing IR camera output and generating a video mask). The processor 342 also runs a video processor or processing module 344, which takes as input the video stream and the IR camera output 326. The camera output is stored in memory 350 as shown at 352. The camera output 352 is processed to generate a defined dynamic water feature 354, which may include the boundary and location of the dynamic feature 314 such as the size, shape, and location of the bubble pattern in the liquid surface as corresponds to reflected IR light 325.

With the dynamic water feature definition 354, the video processor 344 may further act to generate a video mask 356. The video mask 356 may then be used by the video processor 344 to process the input video stream 331 to create the images 348 for projection based on the mask 356. The projector 360 takes this input and outputs 364 an unmasked image 316 on the dynamic water feature 314 as well as a masked portion (video black) that is mapped to the surface 312 for projecting on the portions of the liquid surface 312 free (or substantially free) of the bubbles/agitation by mechanism 318. In this way, the video processor 344 and controller 340 act to control the video projector 360 in response to tracked changes in the liquid surface 312 to provide a high quality image 316 on the dynamic feature 314.

In some cases, though, the video stream 331 is used by a show control system 370 to control agitation mechanism 318 to create the dynamic water feature 314. In such cases, a delay module 346 may be used by the video image controller 340 to calculate or determine a delay in bubbles reaching the liquid surface 312, and the delay time/period is used to determine when to project 364 the image 316 on the surface 312. In such a proactive case, the mask 356 may be generated based on the video stream 331 rather than in response to the IR camera output. For example, similar processing as used by the show control system 370 in controlling the agitation mechanism 318 to create the projection surface 314 may be used to generate mask 356 (map projected image 316 to where bubbles will be created after the calculated delay).

The show control system 370 includes a processor 372 managing memory 380, which stores a show control script 382. For example, the script 382 may define when and which aerators/nozzles are activated in the agitation mechanism 318 to create the dynamic water feature, e.g., bubble pattern changes in size and shape and moves about the surface 312 based on script 382. In some operating modes, the control module 376 run by the CPU 372 retrieves and processes the show control script 382 to generate control signals 386 that are transmitted to the mechanism 318 to cause it to operate and produce the dynamic water feature 314. In other cases, though, the CPU 372 runs a video mapping processor 374 to process the video stream 331 to map pixels associated with imagery in the stream 331 to the liquid surface 312 and/or components of the agitation mechanism 318. In response, the control module 376 acts to generate the control signals 386 based on this processing of the video stream 331.

FIG. 4 illustrates a flow diagram of an exemplary projection process 400 as may be carried out by operation of a projection system described herein such as systems 100C, 100D, 200 and 300. The process 400 starts at 405 such as with selection of a body of water or a source of a liquid surface (such as a fountain system or mist screen) and selection and installation of a bubble generation system to suit the selected source of the liquid surface. Further, step 405 may include installing a tracking system for the liquid surface, selecting and installing one or more projectors for the liquid surface, and providing a video projector controller for controlling the projector(s) and a show system controller (used to control the bubble generation system.).

At 410, the method 400 continues with providing a video server (or data storage media) for use in providing two streams of video (typically, a like video provided concurrently to two differing devices/systems). The video server is communicatively linked (wired or wireless links) to the projector controller and to the show system controller. At 420, the method 400 involves delivering a first digital video media stream to the projector 420 (or to the video controller), and, at 430, delivering a second digital video media stream to a video mapping processor (e.g., part of controller for the bubble generation system).

At 440, the method 400 continues with determining whether an infrared bubble key has been received from an IR video camera positioned and operated to receive IR light reflected from the bubbles/agitated portion of the liquid surface selected in step 405. If not, this step 440 is repeated. If yes, the method 400 proceeds at 450 with the projector controller creating a video mask from the received bubble key (or IR camera output).

At 460, the projector controller inserts a pre-rendered video (e.g., a portion of the first video stream) onto the bubble key to provide/define the unmasked portion of the image to be projected on the dynamic water feature of the liquid surface. Also in step 460, the projector controller acts to create a black mask for all other areas of the liquid surface to create the masked or filtered portion of the projector output for the liquid surface. At 470, a delay is calculated (or a predefined delay retrieved from memory), and the projector controller delays projection of the now masked first video stream from projection by the projector by the delay amount to have projection on the liquid surface (and on the projection surface) to correspond with a rise time of the bubbles (or production time of bubbles).

At step 480, the method 400 includes using a pixel processor/video mapping processor to map the image stream to the liquid surface and then to drive portions (such as air solenoids) of the bubble generation system to selectively generate bubbles to create the dynamic projection surface on the liquid surface. At 490, the method includes operating the projector to project the video stream onto the liquid surface such that the unmasked portion is displayed on the bubbles and the masked portion is displayed (video black or the like) on the other portions of the liquid surface. The method 400 may continue at 440 with receiving an additional bubble key from the IR video camera and updating the video mask to modify the content (shape, size, location) of the first video stream projected onto the liquid surface to suit the moving/changing projection surface. Alternatively, the method 400 may end at 495.

Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter claimed. For example, as discussed above, numerous embodiments of an aeration system or device may be used to practice a projection system, and a relatively low inlet gas pressure (such as low as about 5 pounds per square inch (psi) may be useful in some cases whereas higher pressures (up to 30 to 40 psi or more) may be preferable in other settings) may be utilized to form the dynamic projection system by causing numerous gas bubbles to flow through a planar liquid surface (e.g., a surface of a pond/lake/river, channel, pool, basin, and the like).

Likewise, aeration tubing (or nozzles) may have many arrangements to provide a desired distribution of the gas bubbles (e.g., a simple soaker hose, a tube with small holes, an arrangement with numerous fountain-like nozzles, an aeration stone like those found in fish tanks, and many other arrangements may be used) and the density of such an aeration “manifold” may also be varied (e.g., distance between gas feed/distribution lines and their arrangement in the container/structure holding the liquid may be selected to provide a desired density of bubbles on the liquid surface in the projection screen). In other words, the term bubble generation system is intended to be construed broadly and may include nearly any structure useful for generating air bubbles such as a disk diffuser, a tube diffuser, a blower, or other devices often used in conventional aeration systems (such as pond/lake aeration systems, water treatment facilities, and the like). 

I claim:
 1. A projection system for projecting upon a liquid surface, comprising: an agitation mechanism selectively operable to generate a plurality of gas bubbles on or near the liquid surface; a tracking system tracking at least a location of the gas bubbles on or near the liquid surface; and a projector projecting a video stream onto the gas bubbles based on the location determined by the tracking system.
 2. The system of claim 1, wherein the tracking system comprises an infrared (IR) light source delivering IR light to the liquid surface and an IR video camera receiving a portion of the delivered IR light that is reflected by the gas bubbles.
 3. The system of claim 1, wherein the reflected IR light defines the location of the gas bubbles on the liquid surface.
 4. The system of claim 3, wherein the reflected IR light defines a boundary on the liquid surface around the gas bubbles defining the location of the gas bubbles and a size and shape of a dynamic projection surface provided on the liquid surface by the gas bubbles.
 5. The system of claim 4, wherein the projecting by the projector further comprises generating a video mask based on the boundary around the gas bubbles and applying the video mask to the video stream.
 6. The system of claim 5, wherein an unmasked portion of the video stream is projected by the projector onto a portion of the dynamic projection surface and a masked portion of the video stream is projected by the projector onto portions of the liquid surface outside the boundary.
 7. The system of claim 5, wherein the tracking system operated at least periodically to update the boundary and wherein the projecting includes updating the video mask based on the updates to the boundary.
 8. The system of claim 1, wherein the liquid surface comprises a horizontal planar surface of a body of water and wherein the agitation mechanism comprises a bubble generator operable to change, over time, at least one of the location of the gas bubbles, a size of an area of the liquid surface containing the gas bubbles, and a shape of the area containing the gas bubbles.
 9. The system of claim 1, wherein the tracking system includes an IR camera generating an infrared bubble key, the system further including a video processor generating a video mask from the infrared bubble key, and wherein the projecting includes inserting a portion of the video stream onto the infrared bubble key, whereby the inserted portion is projected onto a portion of the liquid surface including the location of the gas bubbles.
 10. A display system for displaying images on a surface of a body of water, comprising: a light source projecting IR light onto the water surface; an IR-sensitive camera focused on the water surface to receive IR light reflected from the water surface, the IR-sensitive camera generating output based on the received IR light defining a dynamic water feature on the water surface; a video processor receiving output from the IR-sensitive camera and, in response, generating a video mask; and a projector projecting a video stream based on the video mask including projecting an unmasked portion of the video stream onto the dynamic water feature and projecting a masked portion of the video stream onto areas of the liquid surface outside the dynamic water feature.
 11. The display system of claim 10, wherein an input of the IR-sensitive camera is positioned adjacent to an output of the projector.
 12. The display system of claim 10, wherein the dynamic water feature comprises a plurality of air bubbles on or near the water surface.
 13. The display system of claim 12, wherein the dynamic water feature varies over time in one or more of size, shape, and location on the water surface.
 14. The display system of claim 13, wherein the output from the IR-sensitive camera and the video mask are updated at least periodically such that the unmasked portion of the video stream continues to be projected onto the dynamic water feature.
 15. A method of projecting on a surface of a body of water, comprising: first agitating with gas bubbles a first portion of the surface of the body of water; determining a boundary about the first portion; based on the determined boundary for the first portion, projecting a first image onto the first portion; after a period of time, second agitating with gas bubbles a second portion of the surface of the body of water; determining a boundary about the second portion; and based on the determined boundary for the second portion, projecting a second image onto the second portion.
 16. The method of claim 15, wherein the boundaries differ in at least one of size, shape, and location.
 17. The method of claim 15, wherein the determining steps comprise projecting IR light onto the surface and detecting a portion of the projected IR light reflected from the gas bubbles.
 18. The method of claim 17, wherein the projecting of the first and second images comprises, respectively, processing a bubble key corresponding to the first and second portions of the projected IR light reflected from the gas bubbles and inserting at least a portion of the first and second images onto the bubble keys associated with the first and second portions.
 19. The method of claim 18, wherein the projecting of the first and second images further comprises creating black mask for areas on the liquid surface outside the first and second portions using the bubble keys.
 20. The method of claim 15, wherein the first and second agitating comprises sequentially operating a bubble generator provided in the body of water or sequentially operating one or more aeration nozzle of a fountain providing the body of water. 